Thank you for taking your time!
Yes, I think it could be it. I also tried to see in Material Preview differences, and the same color seems different by some reason. For that one I’m not totally sure, I don’t have comparison, but I got feeling that colors now are over-saturated.
Strangely, my initial images have Level with the same amount for Directional Light - 6lux (which isn’t small), and on 5.5 it was looking good.
Again, you provided comparison, it seems good, I’ll mark you answer as Solved. It’s bad that we have such drastic changes. Seems someone didn’t do QA for basic things xD
One more time, thank you for finding differences!